47 A.3d 1038 | Md. Ct. Spec. App. | 2012
On July 1, 2008, Joan Dixon and her husband, Bernard Dixon, brought suit in the Circuit Court for Baltimore City against corporations involved in the manufacturing and distribution of products containing asbestos, including Ford Motor Company, the Georgia-Pacific Corporation (“GP”), Honeywell International, Inc., and the Union Carbide Corporation (“UCC”). Following Mrs. Dixon’s death from pleural mesothelioma, Mr. Dixon pursued her claims as representative of her estate, and the Dixons’ four adult daughters joined their father as plaintiffs, who are now appellants.
Prior to trial, appellants settled with GP, Honeywell, and UCC, but Ford’s cross-claims against those defendants remained for adjudication as potential joint tortfeasors.
Ford moved in limine for a hearing to challenge appellants’ proffered expert on the issue of causation, as well as to exclude the expert’s testimony. Trial commenced on April 15, 2010, and the court denied Ford’s motions, along with certain objections Ford raised during the expert’s testimony.
On April 27, 2010, the jury returned a verdict awarding appellants a total of $15,000,000 in compensatory damages, which the court reduced to $6,065,000 in accordance with the non-economic damages cap of Maryland Code (2006), § 11-108 of the Courts and Judicial Proceedings Article (“CJ”). Ford subsequently filed post-trial motions requesting a new trial and revisions or judgments notwithstanding the verdict (“JNOV”) on both its own cross-claims and appellants’ direct
Questions Presented
The parties’ briefs present a total of eight questions between them,
I. Did the trial court err when it denied Ford’s motion to exclude appellants’ expert epidemiological opinion on “substantial contributing factor causation” where the*184 expert’s testimony did not quantify the probability of causation?
For the reasons that follow, we answer yes and remand the case for a new trial consistent with this opinion.
Factual and Procedural History
Joan Dixon died of pleural mesothelioma on February 28, 2009, having initiated a suit against Ford and various other entities involved in the asbestos market, including GP, Honeywell, and UCC. The complaint alleged that Mr. and Mrs. Dixon “participated in home improvement and maintenance projects throughout the 1960s and 1970s during with [sic] they worked with and around Defendants’ asbestos products,” and that “[throughout the 1950s, 1960s and 1970s, Mrs. Dixon was exposed to asbestos dust created by Mr. Dixon’s work with and around asbestos-containing automobiles and asbestos-containing replacement parts for those automobiles including ... brakes[.]” Appellants further alleged that Mrs. Dixon’s “exposure to Defendants’ asbestos containing products and asbestos containing vehicles and the inhalation of asbestos fibers from the products and vehicles caused her disease and eventual death.”
In response to interrogatories, appellants stated that they “believe Joan Dixon may have been exposed to asbestos through her and her husbands’ use of and exposure to various building materials, including but not limited to Georgia Pacific pre-mixed drywall joint compound which, upon information and belief, contained Union Carbide Corporation’s Calidria brand asbestos.” Deposition testimony established that Mrs. Dixon personally sanded joint compound and cleaned up after at least five home construction and renovation projects.
Appellants sought to introduce Dr. Laura Welch as an expert in asbestos epidemiology and proffered her opinion on causation. Ford did not dispute that Dr. Welch was qualified to render expert testimony on the subject of epidemiology, but instead objected to the methods and substance of her causation opinion. The court denied Ford’s motion,
Q. Now, with regard to your opinions about asbestos and causation which you have given this jury, it’s your opinion, Doctor, that each and every exposure contributes to the development of mesothelioma no matter where it comes from in asbestos exposure; is that right?
A. Right. When somebody has got mesothelioma, all the exposures they have were contributing factors, that’s my opinion.
Q. And it doesn’t matter to you whether the exposure is on a frequent basis, correct?
A. No. I mean, an exposure can be like one event. On a frequent basis, you would be talking about a task or something like that. But I think each one of those discrete exposures is a contributing factor.
Q. So it can be one event in order to be, in your view, a substantial contributing cause to the development of mesothelioma?
A. Correct. It could be one day of work, for example, or something like that.
Q. So it doesn’t have to be a regular course of work? It doesn’t have to be something they do occupationally for a period of time; is that true?
A. No, not necessarily. Because we are talking about somebody who has already got the disease. And I think everyone of the exposures that go into making their sum total of exposure to asbestos is a contributing factor.
Against this general causal backdrop, Dr. Welch explained the basis of her opinion that Mrs. Dixon’s exposure to automobile brake dust was a substantial contributing factor of Mrs. Dixon’s disease:
*187 The easiest way to do that is to turn back to my paper we kept discussing, the Amicus brief that walks through the information that supports a conclusion that brake mechanics are at an increased risk for mesothelioma. So we have a lot of data that the kind of asbestos that’s in brakes, chrysotile, causes mesothelioma. We have a lot of information that brief or low-level exposure to asbestos causes mesothelioma. And I think [plaintiffs’ counsel] had a number of those papers up there on the slides we put together.
And one other part of it is that, as you and I just talked about, asbestos is, in my opinion, the only recognized cause of mesothelioma.
And we know that brake mechanics have exposure to asbestos as has been demonstrated in industrial hygiene studies. There [are] lots of studies that show that exposure occurs. It occurs to [sic] substances known to cause mesothelioma, that people working with friction products get enough asbestos exposure to cause other nonmalignant diseases. And to me, all those studies allow me to say exposure to asbestos by working with brakes can be a substantial contributing cause of mesothelioma.
Dr. Welch admitted that no epidemiological studies had specifically investigated the risk of mesothelioma among wives of brake mechanics. However, Dr. Welch explained that such a study would be practically impossible; if the rate of disease in a group of workers was two-and-a-half cases per hundred thousand—as in the case of mesothelioma—such a study would require thirty-thousand subjects and twenty years to reach a statistically significant conclusion. Instead, Dr. Welch testified that she formed her opinion from the generally accepted fact that asbestos dust left on a worker’s clothing can be transmitted to family members in the home environment.
In its defense, Ford called epidemiologist and risk assessment expert Herman J. Gibb, Ph.D., who testified that none of eighteen epidemiological studies in evidence showed “any evidence that vehicle mechanics have an increased risk of mesothelioma.” By contrast, Dr. Gibb testified that epidemiological studies showed that the risk of mesothelioma among
After the close of evidence, the jury deliberated and returned a verdict against Ford, awarding $5,000,000 to Mrs. Dixon’s estate, $4,000,000 to Bernard Dixon, and $1,500,000 to each of the Dixons’ four daughters, for a total of $15,000,000. After applying the non-economic damages cap of CJ § 11-108, the court entered judgment awarding $5,000,000 to Mrs. Dixon’s estate, $426,000 to Bernard Dixon, and $159,750 to each of the Dixons’ daughters, for a total of $6,065,000. Ford filed a series of post-trial motions seeking a new trial, JNOV, and revised judgments. On March 10, 2011, the court issued a memorandum opinion and order that granted Ford’s request to revise the judgments so as to account for GP as a joint tortfeasor under CJ § 3-1404. Accordingly, the trial court halved the awards to each of the appellants and, on April 21, 2011, entered judgment awarding $2,500,000 to Mrs. Dixon’s estate, $213,000 to Bernard Dixon, and $79,875 to each of the Dixons’ daughters, for a total of $3,032,500 against Ford. Ford’s remaining motions were denied. Appellants and Ford then filed timely appeals, bringing the case before us.
Discussion
Ford argues that the trial court erred when it admitted Dr. Welch’s testimony on the issue of causation and supports its
In Reed, the Court of Appeals adopted the test first articulated in Frye v. United States, 293 F. 1013, 1014 (D.C.Cir.1923), now known in Maryland as the Frye-Reed standard: “[Bjefore a scientific opinion will be received as evidence at trial, the basis of that opinion must be shown to be generally accepted as reliable within the expert’s particular scientific field.” 283 Md. at 381, 391 A.2d 364. In Blackwell v. Wyeth, the Court applied Frye-Reed to a novel theory of causation. Drawing from the Supreme Court’s decision in GE v. Joiner, 522 U.S. 136, 146, 118 S.Ct. 512, 139 L.Ed.2d 508 (1997), the Blackwell Court held that where an expert derives an untested hypothesis from generally accepted theories and research
Despite their perceived differences, the parties in fact agree on the fundamental scientific principles undergirding the expert testimony on both sides. Ford’s amici, among them several eminent researchers and professors,
The question open to scientific debate is the extent to which various asbestos exposures increase the risk of mesothelioma.
We therefore have a settled scientific theory of causation, and it is captured by what philosophers of science call “probabilistic causation,” a logical model that accounts for the inher
[I]n a judicial proceeding in which there is a dispute about the facts of some earlier event, the factfinder cannot acquire unassailably accurate knowledge of what happened. Instead, all the factfinder can acquire is a belief of what probably happened. The intensity of this belief—the degree to which a factfinder is convinced that a given act actually occurred—can, of course, vary. In this regard, a standard of proof represents an attempt to instruct the factfinder concerning the degree of confidence our society thinks he should have in the correctness of factual conclusions for a particular type of adjudication. Although the phrases “preponderance of the evidence” and “proof beyond a reasonable doubt” are quantitatively imprecise, they do communicate to the finder of fact different notions concerning the degree of confidence he is expected to have in the correctness of his factual conclusions.
397 U.S. 358, 370, 90 S.Ct. 1068, 25 L.Ed.2d 368 (1970).
Probabilistic causation is, of course, different in kind from the legal burden of proof. The former is a mental model that
Despite the parties’ (unrecognized) agreement on the science of mesothelioma causation and the conceptual framework that it entails, Ford attacks Dr. Welch’s methodology on the grounds that it is not generally accepted. Specifically, Ford argues that Dr. Welch’s opinion testimony violated the tenets of Blackwell and Balbos by using “downward extrapolation” to arrive at the conclusion that every asbestos exposure is a “substantial contributing factor” in causing eventual mesothelioma. As we now explain, Ford’s argument conflates scientific causation and legal causation in attacking Dr. Welch’s methodology. However, Dr. Welch herself also conflated those concepts, and so her testimony did not “assist the trier of fact to understand the evidence or to determine a fact in issue,” as required by Maryland Rule 5-702.
Like the closely-related concept “proximate cause,” the term “substantial contributing factor” goes beyond the logically simple question of whether the defendant’s action (or inaction) was a “necessary” or “sufficient” condition of harm to the plaintiff. Both proximity and substantiality describe whether “the defendant’s conduct has such an effect in producing the harm as to lead reasonable men to regard it as a cause, using that word in the popular sense, in which there always lurks the idea of responsibility!)]” Restatement (Second) of Torts § 481 (1965). Where the question of causation is probabilistic,
If risk is our measure of causation, and substantiality is a threshold for risk, then it follows—as intimated above— that “substantiality” is essentially a burden of proof. Moreover, we can explicitly derive the probability of causation from the statistical measure known as “relative risk,” as did the U.S. Court of Appeals for the Third Circuit in DeLuca v. Merrell Dow Pharmaceuticals, Inc., 911 F.2d 941, 958 (3d Cir.1990), in a holding later adopted by several courts.
Dr. Welch testified that, in her opinion, “every exposure to asbestos is a substantial contributing cause and so brake exposure would be a substantial cause even if [Mrs. Dixon] had other exposures.” And while we have no doubt that Dr. Welch is well-qualified to render some opinion as to the likely intensity of Mrs. Dixon’s exposure and the likely effect it had on her risk of mesothelioma, Dr. Welch’s testimony implied only that both were “more than nothing.” For obvious reasons an infinitesimal change in risk cannot suffice to maintain a cause of action in tort. Thus, whatever information Dr. Welch conveyed could not possibly have helped the jurors to weigh the substantiality of Ford’s contribution to Mrs. Dixon’s disease. See Moeller v. Garlock Sealing Techs., LLC, 660 F.3d 950, 955 (6th Cir.2011) (explaining that if an opinion that every exposure is substantial “is sufficient for plaintiff to meet his burden, the Sixth Circuit’s ‘substantial factor’ test would be meaningless” (citing Lindstrom v. A-C Product Liability Trust, 424 F.3d 488, 493 (6th Cir.2005))); Gregg v. V-J Auto Parts Co., 596 Pa. 274, 291, 943 A.2d 216 (Pa.2007) (“expert affidavits attesting that any exposure to asbestos, no matter how minimal, is a substantial contributing factor in asbestos disease ... do not suffice to create a jury question in a case where exposure to the defendant’s product is de minim[i]s ...”).
Before we conclude our discussion, we address Ford’s remaining arguments so as to avoid four possible points of confusion. First, Ford complains that “downward extrapolation” is not a reliable method to establish substantial factor causation, but that argument is only trivially true. As we have seen, “substantiality” is a legal concept and not an objective property testable by the scientific method. The contributions of science end at quantitative estimates of exposure and risk. Thus, it is primarily Dr. Welch’s conclusion, and not her methodology, with which we take issue.
Third, we would not use language so strong to describe Ford’s arguments about the “analytical gap” in this case, but Professor Vern R. Walker dispelled similar notions in his
The first [is] the problem of ... finding that a reference group adequately represents the specific individual—that is, that it adequately matches the plaintiff in all causally relevant variables, such as being a woman, being age forty, having no history of cancer in the immediate family, and so forth. The second [is] the uncertainty in assigning a particular probability to the individual case, even when the reference group adequately represents the specific individual. These two major sources of uncertainty can be called, respectively, uncertainty about plaintiff-representativeness and uncertainty about assigning a probability to the individual plaintiff.
Id. at 384-85.
Thus, it could be said that while epidemiology can provide an accurate estimate of general causation among a population that controls for as many variables as possible, actual causation lies outside the bounds of epidemiological inquiry per se. See Reference Manual on Scientific Evidence at 381. Epidemiology informs an opinion of actual causation by establishing general causation, but the link between the two will always require some degree of untested inference and uncertainty, which brings us to our third point of clarification. It would be folly to require an expert to testify with absolute certainty that a plaintiff was exposed to a specific dose or suffered a specific risk. Dose and risk fall on a spectrum and are not “true or false.” As such, any scientific estimate of those values must be expressed as one or more possible intervals and, for each interval, a corresponding confidence
Practical and statistical limitations may have prevented Dr. Welch from providing any particular estimates of Mrs. Dixon’s exposure or relative risk, or from opining with any reasonable certainty that the probability of causation was enough that a reasonable person would consider it substantial. But lack of epidemiological data does not give an expert license to state
JUDGMENTS VACATED. CASE REMANDED TO THE CIRCUIT COURT FOR BALTIMORE CITY FOR NEW TRIAL CONSISTENT WITH THIS OPINION. COSTS TO BE PAID BY APPELLANTS.
. The remaining questions presented were as follows. Appellants asked:
I. Whether the trial court erred in revising the judgment pursuant to Maryland Rule 2-535(a) to affirmatively hold Georgia-Pacific, LLC liable on Ford Motor Company’s cross claim for Mrs. Dixon's mesothelioma[,] contrary to the jury’s verdict.
II. Whether portions of the statutory cap on non-economic damages found at Md.Code, § 11-108 of the Courts and Judicial Proceedings Article as applied in this case violates [sic] the equal protection clause of the U.S. Constitution and Article 24 of the Maryland Declaration of Rights.
In addition to the question presented, above, Ford asked:
II. Whether the trial court abused its discretion by failing to exclude the specific causation opinion of Dr. Laura Welch that Mrs. Dixon’s alleged secondary exposure to asbestos from her husband’s work with Ford brake linings was a substantial contributing factor in causing her mesothelioma, where that opinion was offered in response to a hypothetical question that assumed facts not adduced in evidence?
III. Whether the trial court erred in denying Ford’s Motion for New Trial given that (a) the jury’s verdict was inconsistent and against the great weight of evidence, (b) Plaintiff’s closing arguments were highly improper and prejudicial, and (c) the verdict was shocking.
IV. Whether the trial court erred in failing to enter judgment against the remaining Cross-Defendants in the matter, given the uncontradicted evidence presented with respect to their liability at trial?
. The trial court summarized Mrs. Dixon's exposure to dry wall joint compound in a post-trial memorandum:
Mr. Dixon, Mrs. Dixon, and the Dixon’s daughters testified that Mrs. Dixon personally sanded joint compound and that she would become so covered in dust that she became "white.” Mrs. Dixon testified that they used Georgia Pacific Ready Mix compound while doing textured ceilings at their home in 1966; Mr. and Mrs. Dixon*185 both testified that they used Georgia Pacific joint compound when they built the beauty shop addition in 1971, and that Mrs. Dixon sanded drywall. They also used Georgia Pacific joint compound when they put up drywall and renovated their garage at the same time. The family built a bedroom in the basement of their home in the early 1970s, and Mrs. Dixon used Georgia Pacific joint compound to finish the drywall. Mrs. Dixon was also exposed to the Georgia Pacific compound Mr. Dixon used when he renovated the basement, renovated Mrs. Costello’s house, and did construction with Allen and Harry Paul which included putting up and sanding drywall. At Ms. Costello's house, her daughter remembers Mr. Dixon working with the green and white buckets that were identified as Georgia Pacific joint compound.
In addition, Mrs. Dixon was exposed to Georgia Pacific joint compound when she and Mr. Dixon built the family meat store and apartments in 1976. Mrs. Dixon testified that she used Georgia Pacific Ready Mix joint compound to finish the drywall work in the apartments from 1976 to 1977. Mr. Dixon testified that she did the drywall work in the same manner as the work she had previously done, including sanding, cleaning, and doing the laundry. During the relevant time period when Mr. and/or Mrs. Dixon performed home renovation work, Mrs. Dixon did the laundry.
. Dr. Welch was admitted as an expert in occupational medicine, internal medicine, epidemiology of asbestos disease, and the diagnosis of asbestos disease.
. Dr. Welch had earlier given her assessment of various epidemiological studies finding no evidence of increased mesothelioma risk among auto workers:
I think the group of studies have such significant limitations, they don’t—they conclude—or an overall analysis of them concludes that asbestos exposure in brakes does not cause mesothelioma, but a study that doesn't find something doesn’t mean there is no relationship.
You have to look at the studies and see whether they are capable of answering the question. I think the limitations of those studies is so significant that they don't really answer the question. They don’t give us any good information on the question.
. Among other well-credentialed scientists, the amici include James D. Watson, Ph.D., the Nobel laureate best known as a co-discoverer of the structure of DNA, Dudley Herschbach, a Nobel laureate in chemistry and professor of science at Harvard University, Richard Wilson, D.PhiL, research professor of physics at Harvard University, and Patricia Buffler, Ph.D., professor of epidemiology at the School of Public Health of the University of California at Berkeley.
. The DHHS reported that one of several “unresolved issues” is “the actual risks for malignant or nonmalignant respiratory disease that may exist at exposure levels below air concentrations (0.1-0.2 fiber/mL) established as recent occupational exposure limits,” and noted the following findings:
Lung Cancer and Mesothelioma: Based on an analysis of data from epidemiologic studies of workers who were exposed to asbestos before modern occupational exposure limits were established, EPA (1986) calculated by extrapolation that lifetime exposure to asbestos air concentrations of 0.0001 fiber/mL could result in up to 2 to 4 excess cancer deaths (lung cancer or mesothelioma) per 100,000 people. This air concentration is within reported ranges of ambient air levels (0.00001 to 0.0001 fiber/mL). The EPA analysis has been extensively discussed and reviewed in the scientific literature (Camus et al.1998; Hodgson and Darnton 2000; Hughes 1994; Landrigan 1998; Lash et al.1997). EPA is in the process of reviewing and possibly updating their [sic] cancer risk estimates for asbestos.
Toxicological Profile for Asbestos at 24 app. F.
. The other motivation for probabilistic causation—which lies well beyond the scope of this discussion—is the possibility that the physical universe is physically indeterminate, which remains a topic of debate among some of the world’s greatest minds. We need not resort to any assumption about determinism, however, for the necessary presence of uncertain factual inquiries in law justifies our use of the probabilistic model.
. The model can also describe a non-deterministic universe, but that is certainly beyond the scope of this discussion. See Probabilistic Causation, cited above.
. For an extended discussion of “subjective probability,” see Vern R. Walker, Preponderance, Probability, and Warranted Factfinding, 62 Brooklyn L.Rev. 1075, 1080-92 (1996).
. It also appears that, in this context, "substantiality” is an analogue of "proximity” in that it asks what factors must be considered in assessing the risks of exposure: must we account for the fact that a plaintiff smoked, was exposed to other sources of asbestos, or is biologically susceptible to cancer? Stated in terms of probabilistic causation, proximate causation would determine the set of "constants” to be used in testing and calculating the conditional probabilities of harm with and without exposure.
. See, e.g., Daubert v. Merrell Dow Pharms., Inc., 43 F.3d 1311, 1320 (9th Cir.1995) (opinion on remand from Daubert v. Merrell Dow Pharms., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993)), cited with approval in In re Hanford Nuclear Reservation Litig., 292 F.3d 1124, 1137 (9th Cir.2002) (adding that, "when available, known individual risk factors are also relevant”); In re Breast Implant Litig., 11 F.Supp.2d 1217, 1225-1226 (D.Colo.1998) ("Plaintiffs must present expert testimony demonstrating that exposure to breast implants more
. In Daubert II, 43 F.3d at 1320-21, the U.S. Court of Appeals for the Ninth Circuit held that causation under a preponderance standard is equivalent to a "relative risk" of two. In other words, the Daubert court held that a plaintiffs risk of injury must have at least doubled in order to hold that the defendant's action was "more likely than not” the actual cause of the plaintiff’s injury. The problem with this holding is that relative risk does not behave like a "binary” hypothesis that can be deemed "true” or "false” with some degree of confidence; instead, the uncertainty inherent in any statistical measure means that relative risk does not resolve to a certain probability of specific causation. In order for a study of relative risk to truly fulfill the preponderance standard, it would have to result in 100% confidence that the relative risk exceeds two, which is a statistical impossibility. In short, the Daubert approach to relative risk fails to account for the twin statistical uncertainty inherent in any scientific estimation of causation. See Steve Gold, Note, Causation in Toxic Torts: Burdens of Proof, Standards of Persuasion, and Statistical Evidence, 96 Yale L.J. 376, 384 (1986) (failure to distinguish between "fact probability” and "belief probability” "works
All of this is not to say, however, that any and all attempts to establish a burden of proof of causation using relative risk will fail. Decisions can be—and in science or medicine are—premised on the lower limit of the relative risk ratio at a requisite confidence level. The point of this minor discussion is that one cannot apply the usual, singular "preponderance” burden to the probability of causation when the only estimate of that probability is statistical relative risk. Instead, a statistical burden of proof of causation must consist of two interdependent parts: a requisite confidence of some minimum relative risk. As we explain in the body of our discussion, the flaws in Dr. Welch's testimony mean we need not explore this issue any further.
. Appellants cite ACandS, Inc. v. Abate, 121 Md.App. 590, 710 A.2d 944 (1998), lor the proposition that "Maryland jurisprudence does not require proof of an individual’s dose of asbestos in order to prove substantial factor causation as articulated by Balbos." But appellants overstate the conclusion of ACandS, in which we said that "[w]e shall not hold that a plaintiff in any asbestos case must present expert testimony as to the amount of respirable asbestos fibers emitted by a particular product.” Id. at 671, 710 A.2d 944 (emphasis added). Our decision did not address whether exposure—or risk—must be quantified because, "[ujnder the peculiar circumstances of this particular case, the evidence against [the defendant] was sufficient without such testimony.” Id. The circumstances of this case are "peculiar” in a different way: they present such attenuated evidence of exposure and risk that the jury could not possibly weigh substantial factor causation without the aid of expert testimony. And as our discussion has shown, one can draw no conclusions about probabilistic causation without estimated quantities of exposure and risk.
. See Federal Judicial Center, Reference Manual on Scientific Evidence 91 (2d ed. 2000) (" 'Anecdotal evidence’ means reports of one kind of event following another. Typically, the reports are obtained haphazardly or selectively, and the logic of 'post hoc, ergo propter hoc' does not suffice to demonstrate that the first event causes the second.”). See also Haggerty v. Upjohn Co., 950 F.Supp. 1160, 1163-64 (S.D.Fla.1996) ("anecdotal case reports appearing in medical literature ... can be used to generate hypotheses about causation, but not causation conclusions” because "scientifically valid cause and effect determinations depend on controlled clinical trials and epidemiological studies”).
. Professor Walker does not invoke this legal phrase, but the “inferential gaps’’ addressed in his article could have no other meaning.
. Professor David Rosenberg succinctly stated this principle in his article, The Causal Connection in Mass Exposure Cases: A "Public Law" Vision of the Tort System, when he wrote:
The entire notion that "particularistic” evidence differs in some significant qualitative way from statistical evidence must be questioned. The concept of "particularistic” evidence suggests that there exists a form of proof that can provide direct and actual knowledge of the causal relationship between the defendant's tortious conduct and the plaintiff's injury. "Particularistic" evidence, however, is in fact no less probabilistic than is the statistical evidence that courts purport to shun. “Particularistic” evidence offers nothing more than a basis for conclusions about a perceived balance of probabilities.
97 Harv.L.Rev. 849, 870 (1984) (footnotes omitted). See also Walker, Preponderance, Probability, and Warranted Factfinding, 62 Brooklyn L.Rev. at 1080-92.
. For the sake of simplicity, we refer to exposure in the abstract and need not account for its various relevant dimensions, such as the frequency and duration of exposure. These factors are generally accounted for in scientific literature by measuring exposure as a matter of both time and concentration. See Toxicological Profile for Asbestos at 17 ("Inhalation exposure is [] generally regarded as cumulative, and exposures have been expressed in terms of concentration of fibers over time or PCM fiber-years/mL (f-yr/mL).”). Thus, Dr. Welch could have inferred from existing research how likely it was that Mrs. Dixon’s exposure fell above, below, or between various fiberyears/mL values.
. As noted, above, mesothelioma risk has been studied and estimated for asbestos exposures as low as natural atmospheric levels. Further
